Lattice boom construction



June 6, 1967 G. s. ALLEN, SR

LATTICE BOOM CONSTRUCTION 4 Sheets-Sheet 1 Filed Sept. 21, 1965 INVENTOR. @z'ORGE S. ALL/M31 2. BY

June 1957 G. s. ALLIN, SR 3,323,650

LATTICE BOOM CONSTRUCTION Filed Sept. 21, 1965 4 Sheets-Sheet 2 a lINVENTOR. Kg GEORGE S. ALLIN, SR.

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INVENTOR. GEORGE S. mum, rm.

4 Sheets-Sheet 5 June 6, 1967 G. s. ALLIN, an

LATTICE BOOM CONSTRUCTION 4 Sheets-Sheet 4 Filed Sept. 21, 1965 m a NU mE MM f E 57 6 Wm m d EYW 6 United States Patent 6 3,323,660 LATTIQE1390M CONSTRUCTION George S. Allin, Sn, Green Bay, Wis., assignor toNorthwest Engineering Corporation, Green Bay, Wis, a corporation ofWisconsin Filed Sept. 21, 1965, Ser. No. 488,872 8 Claims. (Cl. 212144)This invention relates to lattice boom construction and includes bothnovel structural features and a novel method of construction for latticebooms employed in large cranes, shovels and the like.

In the past it has been customary to individually weld the ends of thelattice members directly to the correspond ing chords. This had atendency to introduce stresses in the chords that could not be relievedand which often produced distortion of the entire boom. Where severallattice members were welded to a chord in close proximity the stressconcentrations were aggravated and frequently resulted in cracks in thechord, thus weakening the entire boom.

. The danger of booms breaking under load and falling is becoming moreof a concern with the use of long lightweight booms on erection cranesfor modern tall buildings.

The present invention provides a boom construction that strengthens thechords instead of weakening them and that facilitates securing of thelattice members to the chords while introducing a minimum of weldstresses into the chords.

The invention is applicable to booms having angle iron chords withflanges or legs at right angles to each other and also to booms havingtubular chords. When angle iron chords are employed the inventionemploys a connector that fits into the bosom of the chord and is weldedto both legs, thus adding support to the legs and strengthening thechords. When tubular chords are employed the invention employs a partialsleeve-like connector that fits approximately a 180 circumferentialportion of the chord and strengthens the same.

The connectors are welded to the chords and the latter may then bestress relieved to assure freedom from undesirable locked in weldingstress. Thereafter the lattice members are welded to the connectors ofspaced chords to complete the boom assembly. The welds for the latticemembers are desirably spaced from the chords so as not to directlystress the latter. Thus the predetermined relation and position of thechords can be maintained without distortion.

Where it is desired to reduce the weight of the boom by the employmentof heat treated chords and lattice members, the construction provides atype of welded joint that makes possible the joining of the memberswithout losing the effect of the heat treatment therein.

The accompanying drawings illustrate the best mode presentlycontemplated for carrying out the invention.

In the drawings:

FIGURE 1 is a top plan view of a boom segment employing angle ironchords and incorporating the connector of the invention;

FIG. 2 is a side elevation of the boom segment of FIG. 1;

FIG. 3 is an enlarged transverse section taken on line 3-3 of FIG. 1;

FIG. 4 is a detail section taken transversely of a chord on line 4--4 ofFIG. 2;

FIG. 5 is a detail section taken on line 5-5 of FIG. 4 and showing aconnector with its attachment to the chord and to the ends of aplurality of lattice members;

FIG. 6 is a perspective view of a portion of a chord with a connectorsecured thereto and adapted to receive the ends of three latticemembers;

FIG. 7 is a view similar to FIG. 6 and showing a connector adapted toreceive the ends of six lattice members; FIG. 8 is a detail sectionshowing an end connector;

FIG. 9 is a detail plan view of an end connection at one corner of twobeam sections;

FIG. 10 is a detail enlarged transverse section of one type of endconnection taken on line 1010 of FIG. 1;

FIG. 11 is a detail enlarged transverse section of the other type of endconnection taken on line 1111 of FIG. 1; and

FIG. 12 is a perspective view of a portion of a boom segment made up oftubular chords.

The boom illustrated is constructed of sections joined end to end andwhich may vary in dimensions according to their position in the boom.Sections disposed near the base or in the central body region of theboom may have their chords substantially parallel. Sections disposednear the outer end of the boom will generally be tapered to a smallercross sectional dimension toward the outer end, by disposing the chordsat a predetermined angle to each other.

In the embodiment illustrated in FIGS. 1-9, the boom section 1 is madeup of four generally parallel angle iron chords 2, 3, 4 and 5,respectively, and a plurality of cross lattice or lac ng members anddiagonal or lacing members more specifically identified hereinafter.

The lattice members converge adjacent the chords to form a series ofplanular transverse strengthening zones, generally indicated in FIGURE 1as zones A, B, C, D, E, F and G, respectively.

At each of these strengthening zones a connector is employed to securethe lattice members to a corresponding chord. Thus, at the end zones Aand G, two types of connectors 6 and 7 are employed as individuallyillustrated respectively in FIGS. 10 and 11. Similarly, at each of zonesB, C, D, E and F, two types of intermediate connectors 8 and 9 areemployed as individually illustrated in FIGS. 6 and 7.

More specifically chords 2 and 4 have the following connectors securedthereto in the order named starting with zone A and ending with zone G:connectors 6, 9, 8, 9, 8, 9 and 6. Similarly chords 3 and 5 have thefollowing connectors secured thereto in the order named starting withzone A and ending with zone G: connectors '7, 8, 9, 8, 9, 8, and 7.

Each intermediate connector as illustrated in FIGS. 47, inclusive, is acasting adapted to fit in the bosom of a chord at a selected zone. Theconnector is a convex member having its opposite edges welded as at 10and 11 to the corresponding legs 12 and 13 of the chord. The connectorsbridge the angle of the chord and support the legs relative to eachother, thereby strengthening the chord at each zone.

Each connector 6 and 7 is adapted to receive the end of two latticemembers 14 and 15 disposed at right angles to each other and in thetransverse plane of the zone. Lattice member 14 extends from connector 6on chord 5. Lattice member 15 extends at right angles to thecorresponding lattice member 14 and from connector 6 on chord 2 toconnector 7 on chord 5 and a similar lattice member 15 extends fromconnector 6 on chord 4 to connector 7 on chord 3. Thus the two latticemembers 14 and the two lattice members 15 at each end of section 1 forma rectangular outline corresponding to the rectangular cross section ofthe boom section 1.

Associated witheach connector '7 is an angular connector 16 whichreceives and secures two diagonal lattice members 17 and 18 extending atan angle toward a corresponding connector 9 on an adjacent chord, i.e.,the member 17 extending from connector 16 on chord 3 to connector 9 onchord 2 and member 18? extending from connector 16 on chord 3 toconnector 9 on chord 4. Similar lattice members 17 and 18 join aconnector 16 associated with connector 7 on chord to the respectiveconnectors 9 on chords 4 and 2.

The connectors 6 and 7 at each end of the boom section 1 have means forsecuring the section to the end of an adjacent similar section. Variousmeans may be employed for this purpose, that shown comprising one ormore cars 19 on the connectors and disposed to fit adjacentcorresponding ears on the next adjacent section. The connectors at oneend of boom section 1 have one ear 19 while the connectors at theopposite end of boom section 1 have two ears 19 spaced apart to receivethe single ear of a corresponding end connector of an aligned boomsection, as shown in FIG. 9. Each ear 19 has a bore 20 therethrough forreceiving a pin 21 and which passes through the aligned bores ofadjacent ears when two similar sections are aligned for securing thesame together.

The end connectors 7 provide an additional diagonal socket 22 forreceiving a diagonal lattice member 23 which extends laterally in atransverse plane normal to boom section 1 and between the connector 7 onchord 3 in zone A and the connector 7 on chord 5 in the same zone. Atthe opposite end of boom section 1, in zone G the lattice member 23 mayextend between the connectors 7 on the same chords 2 and 4.

Referring to zone B, as illustrated in FIGS. 1 and 2, a connector 9 iswelded to each of chords 2 and 4, and a connector 8 is welded to each ofchords 3 and 5. The same is true at zones D and F, zone D beingadditionally illustrated in FIG. 3.

Referring to zone C, as illustrated in FIGS. 1 and 2, a connector 9 iswelded to each of chords 3 and 5, and a connector 8 is welded to each ofchords 2 and 4. The same is true at zone E.

Connector 9 is specifically shown in FIG. 7 and has six holes orfittings for receiving the ends of tubular lattice members. As shownthere are three circular openings or fittings on a side, the centralsocket or fitting 24 being generally perpendicular or normal to theopposite leg of the chord, and the two end sockets or fittings 25 and 26on each side being disposed at suitable angles to receive diagonallattice members as shown in FIGS. 4 and 5.

As shown in FIG. 1, one of the fittings 25 of connector 9 on chord 2receives diagonal lattice member 17 from the connector 16 on chord 3,and as shown in FIG. 2, one of the fittings 25 of connector 8 on chord 4receives diagonal lattice member 18 from the connector 16 on chord 3.Similarly, the other fitting 25 of connector 9 on chord 2 receives adiagonal lattice member 18 from the connector 16 on chord 5 and theother fiitting 25 of connector 9 on chord 4 receives diagonal latticemember 17 from the connector 16 on chord 5.

The fittings 26 of each connector 9 on chords 2 and 4 at zone B securediagonal lattice members 27 and 28, respectively, which extend to thecorresponding fittings 25 of connectors 9 on chords 3 and 5 at zone C.Similarly the fittings 26 of each connector 9 at each of the zonessecure diagonal lattice members 27 and 28, respectively, extending tothe fittings 25 of corresponding connectors 9 at the next succeedingzone.

The central fittings 24 of each conector 9 secure lattice members 29 and30 which extend at right angles to each other to corresponding fittings31 in connectors 8 on adjacent chords.

Connectors 8 are illustrated in FIG. 6 and each has the two sockets orfittings 31 disposed at right angles to each other and generallyperpendicular to the opposite leg of the chord. In addition to fittings31, each connector 8 has an intermediate diagonal fitting 32, as shownin FIGS. 3 and 6 and which secures a strut 33 that extends diagonally ofthe section, i.e. from one chord to the chord diagonally oppositethereto,

More specifically, as shown in FIG. 3, at zone D 4 the connector 8 onchord 3 has a fitting 32 which secures one end of the diagonal strut 33,and the similar connector 8 on chord 5 has a fitting 32 which securesthe other end of the diagonal strut 33. Since chords 3 and 5 arediagonally opposite in the boom structure struts 33 serve to brace thestructure diagonally. Similar struts 33 join the diagonally oppositeconnectors 8 at zones B and F. At zones C and E struts 34 join thecorresponding connectors 8 and extend diagonally between chords 2 and 4.

In assembling the boom section, after the connectors are welded to theindividual chords and the latter properly stress relieved, the fourchords are generally positioned in a fixture and the lattice members andstruts are individually positioned and welded in place. In positioninglattice members and struts one end is first inserted into a socket orfitting far enough to permit the member or strut to be aligned with theopposite fitting, whereupon a slight retraction of the member or strutwill result in both ends of the same being confined in the correspondingfittings. Thereafter a fillet Weld 35 around the tubular member or strutwill secure it to the fitting at each end.

It will be noted that welds 35 are generally spaced from welds 10 and 11and from the chords so that stresses resulting from welds 35 are notconcentrated in the chords and do not weaken them.

If a lattice member or strut becomes damaged in service of a boom, it ispossible to cut the member or strut out and replace it with a new onewithout injury to or stressing the adjacent chords.

FIG. 12 illustrates an embodiment of the invention employing tubularchords 36 and in which the connectors 37 are half sleeves thereon havingthe desired projecting sockets or fittings 38 for securing the latticemembers and struts. In this construction the half sleeves 37 greatlystrengthen and support the chords at the junction zone for the latticemembers.

Half sleeves 37 are welded to the chords by fillet welds 29 along theperipheral edges of the half sleeves.

The detail description given above is illustrative only, and variousmodifications and embodiments may be employed. The principle involved isto keep the welds for the various lattice members and struts away fromthe chords and to provide an intermediate connector that bothstrengthens the chords and cushions or relieves the stress under workingloads.

By employing fillet welds with the chord or lattice member extendingbeyond the weld in both directions, it is possible to keep the heatinput low enough during the welding process to effect a quenching of theweld by the mass of metal adjacent to it without removing the desiredhigh strength of a previously heat treated chord or lattice member.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following clalms particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:

1. For use in connecting lacing members to angle iron chords in a boomframework, a connector comprising a unitary body shaped to closely fitin the bosom of a chord and to be welded thereto, said unitary bodyhaving a plurality of openings therein remote from the chord welds andadapted to receive and secure the ends of boom lacing members.

2. In a boom having a plurality of longitudinally extending angle ironchords, a plurality of connectors fixedly secured in the bosom of eachof said chords, each of said connectors having a plurality of openingstherein, and lacing members disposed with their ends secured in saidopenings and extending between connectors on different chords.

3. In a boom having a plurality of longitudinally extending angle ironchords, a plurality of connectors fixedly secured in the bosom of eachof said chords, each of said connectors having a plurality of openingstherein which are disposed in the same plane, at least some of saidconnectors having an additional plurality of openings disposed in aplane which intersects said first-named plane, each said opening beingaligned with a corresponding opening in a connector on a differentchord, and lacing members disposed with their ends secured incorresponding aligned openings and extending between connectors ondifferent chords.

4. A boom made up of sections, each comprising a plurality oflongitudinally extending chords, a plurality of connectors spacedlongitudinally of each chord and secured thereto by welds, each saidchord and the connectors welded thereto being stress relieved as a unit,a plurality of lattice members joining connectors on adjacent chords tospace the chords from each other, and welds securing said latticemembers to said connectors and generally remote from said first namedwelds to facilitate replacement of a lattice member without effectingthe characteristics of the chords to which it is secured.

5. The construction of claim 4 in which the welds are of a fillet typewith the corresponding chord or lacing member extending both directionstherefrom.

6. A boom made up of sections, each comprising a plurality oflongitudinally extending angle iron chords, a plurality of connectorsspaced longitudinally of each chord and secured in the bosom thereof bywelds to the adjacent legs of the chord, each said chord and theconnectors Welded thereto being stress relieved as a unit, a pluralityof lattice members joining connectors on adjacent chords to space thechords from each other, and welds securing said lattice members to saidconnectors and generally remote from said first named Welds tofacilitate replacement of a lattice member Without effecting thecharacteristics of the chords to which it is secured.

7. A boom made up of sections, each comprising a plurality oflongitudinally extending tubular chords, a plurality of partialsleeve-like connectors spaced longitudinally of each chord and securedthereto by welds along the periphery of the connectors, each said chordand the connectors welded thereto being stress relieved as a unit, aplurality of lattice members joining said connectors on adjacent chordsto space the chords from each other, and welds securing said latticemembers to said connectors and generally remote from said first namedwelds to facilitate replacement of a lattice member without effectingthe characteristics of the chords to which it is secured.

8. In the manufacture of boom sections from longitudinal chords andtransverse and diagonal lattice members, positioning a series ofconnectors in longitudinally spaced relation along each chord, weldingsaid connectors to the corresponding chord, stress relieving the chordand connectors after said welding, assembling the chords for eachsection, individually positioning lattice members between connectors ondifferent chords and welding said members to said connectors atpositions generally remote from said first named stress relieved welds.

References Cited UNITED STATES PATENTS 1,760,955 6/1930 Moss. 2,149,8443/ 1939 George. 2,219,599 10/ 1940 Penote. 3,021,014 2/1962 Korensky212-144 ANDRES H. NIELSEN, Primary Examiner.

1. FOR USE IN CONNECTING LACING MEMBERS TO ANGLE IRON CHORDS IN A BOOMFRAMEWORK, A CONNECTOR COMPRISING A UNITARY BODY SHAPED TO CLOSELY FITIN THE BOSOM OF A CHORD AND TO BE WELDED THERETO, SAID UNITARY BODYHAVING A PLURALITY OF OPENINGS THEREIN REMOTE FROM THE CHORD WELDS ANDADAPTED TO RECEIVE AND SECURE THE ENDS OF BOOM LACING MEMBERS.